What's next in the network: software defined networking

A type of networking architecture on the rise (and a term you might start hearing at conferences) is software defined networking (SDN), an approach that opens up routers and switches that once were closed to allow for optimizing their performance within a network. The process starts with separating the control plane from the data plane within the equipment.

In a traditional router or network switch, the control plane is the part whose job is to draw the map of the network as well as the information in the routing table. The data (or forwarding) plane’s job is to read the routing table in order to determines what to do with incoming information packets. Usually these are both actual pieces of hardware that are physically in the device.

In some SDN setups, the two planes are decoupled from each other, and the control plane is actually implemented in software in a server. This can increase bandwidth considerably, as network devices can react more quickly to routing requests. It can also dynamically filter inbound packets to make the switch function as a simple firewall. This methodology can also allow a switch to help with load balancing by rewriting packet headers according to its load balancing policy.

The focus of SDN involves the programmed manipulation of the networking equipment, whether or not there is an actual decoupling of the two planes. This is because Cisco recently announced what it calls an application programming interface (API) with many of their platforms as part of their SDN offerings. Of course, most other manufacturers are following suit, so now the standard definition is changing focus.

The standard that is formulating around this concept is called the OpenFlow protocol. This was developed at Stanford in 2009, and taken over by the Open Networking Foundation in 2011. The ONF is the prime motivator for the standardization of SDN.

Of course, as more vendors make larger investments in SDN development, the emerging standard could change again. As it settles down, look for a slough of product announcements. But while the ONF is trying to get all the Open Flow ducks in a row, the network administrator will have to look closely at the specs of each device.

As the standard starts to solidify, we will keep you posted.

About the Author

Greg Crowe is a former GCN staff writer who covered mobile technology.